In a conventional Energy Recovery Linac (ERL) the spent electron beam energy is not completely recovered. As shown in FIG. 1, an ERL includes an electron gun 10 that injects high energy particles, such as electrons, through a booster 12, into a beam line 14. Magnets 16 direct the path of the electrons through a linac (linear accelerator) 18 which increases the speed and energy of the electrons. Bending magnets 20 direct the beam 22 through a user device 24 and again through the linac 18 in which the unused beam energy is recovered. The spent beam 26 is then stopped in a high power beam dump 28, which results in several MeV of wasted energy. The booster 12 is not energy recovered and the spent beam 26 still contains a lot of energy that must be absorbed in the beam dump.
As shown in FIG. 2, low power RF 30 is input to the linac 18 to accelerate the electrons. In the conventional ERL, the booster 12 requires a substantial amount of high-power RF 32 to accelerate the high current beam 22. The spent beam 26 contains a lot of energy that must be absorbed in the high power beam dump 28 and may produce a serious radiation hazard.
Accordingly, there is a need to recover the energy in a spent beam with high efficiency and transfer the energy back to a consumer for reuse, such as to the ERL injector cryomodules. Such an energy recovery method would be advantageous to any accelerator facility with a dumped beam, such as a beam stop, with a beam power considerably high such that a recovery would yield a significant RF energy and cost saving.